Data collected so far demonstrate that vHipp fibers are uniquely concentrated in the medial NAc shell. In this region vHipp input is predominant and selectively strengthened following cocaine injections. Bidirectional optogenetic manipulations in vivo have shown that vHipp input to the NAc drives cocaine-induced locomotion. The most notable finding thus far is that optical stimulations designed to offset the differential potency of each afferent pathway have proved that each excitatory input can reinforce instrumental behavior. These results suggest that the specific excitatory pathway activated is not as important as how much glutamate is released into the NAc, at least in terms of generating motivated behaviors.